Substituted and unsubstituted arylethylamines and their salts are chemical intermediates of commercial significance. They are used in the preparation of pharmacologically active compounds and in some instances are themselves pharmacologically active. For example, phenethylamine and p-hydroxyphenethylamine (Tyramine) have sympathomimetic (adrenergic) action. Tyramine is also a moiety in opiates, and is useful as an intermediate or substituent in the preparation of other physiologically active compounds or compositions. Tyramine hydrochloride is an important pharmaceutical intermediate used for the preparation of bezafibrate, an anticholesterol agent. Hydroxytyramine (dopamine) is a pharmacologically important neural inhibitory transmitter. It is the active ingredient in Dopastat and Intropin, and it also represents the naturally occurring immediate precursor of norepinephrine.
Because of the importance of arylethylamines and their salts, accounts of their synthesis are well known. Some of them are: U.S. Pat. Nos. 1,995,709; 2,567,906; 2,505,645; 2,784,228; and 3,966,813; Journal of Medicinal Chemistry, vol. 25, p. 1442 (1982); J. Chem. Society. Vol. 95, p. 1127 (1909); J. Amer. Chem. Society. Vol. 55, p. 3389 (1933), and Hakko Kogaku Kaishi, Vol. 55(2), pp. 68-74 (1977).
U.S. Pat. No. 5,041,669 (assigned to Hoechst Celanese Corporation) describes the synthesis of arylethylamines from arylmethyl ketones. The ketones are converted to aryl .alpha.-oximinoalkyl ketones which are then hydrogenated to arylethylamines.
Pending U.S. patent application Ser. No. 07/630,127, filed Dec. 19, 1990, now abandoned, describes the synthesis of arylethylamine hydrochlorides by hydrogenation reduction of aryl .alpha.-oximinoalkyl ketones in an aqueous reaction medium.
There is a continuing interest in identifying improved and cost effective methods to prepare arylethylamines, preferably from readily available materials, or materials that may be produced readily and economically such as, for example, (.alpha.-chloro-.alpha.-oximino)acetophenones. Synthesis of (.alpha.-halo-.alpha.-oximino)acetophenones is known. For example, U.S. patent application Ser. No. 07/801,999, filed Dec. 3, 1991, describes the synthesis of 4-hydroxy (.alpha.-chloro-.alpha.-oximino)acetophenone (N,4-dihydroxy-.alpha.-oxobenzene-ethanimidoyl chloride). Compounds like 4-hydroxy (.alpha.-chloro-.alpha.-oximino)acetophenone are known to yield aryl aminoethanol hydrochlorides on reduction with lithium aluminum hydride, according to H. Brachwitz, Zeitschrift fur Chemie. Vol. 14(7), 268 (1974).